ocr: CASSEGRAIN FOCUS SECONDARY MIRROR PRIMARY, - - - - - - - - - 4 hy - - . / - - MIRROR - - LA - - - - ' - - 9 LIGHT - - - - - - - - à - - - - RAYS - - - - - - - - - - - - 4 U - - - - - - - - - - I - - - a - X - - - - - . à - - - - REAL IMAGE Coudé Focus The primary mirror forms an image in a position that is difficult to observe. In the Cassegrain focus, a secondary mirror reflects the light back through a hole in the primary mirror. A camera can view the image without blocking the incoming light.
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